Abstract: The effect of bonding time on the bonding strength of thick aluminum wire wedge bonding was studied under different ultrasonic power conditions.The shear strength is the criterion of bonding strength.The experiments show that:(1) Bonding strength is sensitive to the bonding time when the ultrasonic power is low,and insensitive when the ultrasonic power is high.(2) For short bonding time,the primary failure are peeled off and non-stick,which indicated that the diffusion of interface is insufficient.(3) For long bonding time and large ultrasonic power,the failure state is break,which illuminated that the diffusion of interface is sufficient,and the durative vibration causes fatigue crack in the aluminum wire.